1. Field of the Invention
The present invention relates to pushing tools, and more particularly to a tool which automatically clamps itself to one environmental object while simultaneously exerts a pushing force on a second environmental object. An illustrative application is in the field of carpentry. The tool anchors itself to, for example, a joist, while exerting a pushing force on a board which is to be nailed to that joist. Fields other than carpentry can benefit from the invention. Wherever there is an object requiring force to move beyond that which a person can reasonably exert, and that object is in close proximity to a fixed point of anchorage, the present invention can profitably be brought to bear on the object being moved.
2. Description of the Prior Art
Professional carpenters, home owners, hobbyists, and others engaging in carpentry from time to time encounter situations wherein rough and semi-finished lumber pieces such as planks and boards are warped to the point that they are barely if at all acceptable for being installed in a construction project. It is usually desired that buildings and other projects have straight, flat surfaces and perpendicular angles between boards. Warped boards and planks degrade suitability of the completed project. However, economics dictate that commercial supplies of rough and semi-finished lumber usually include warped pieces. The craftsman must deal with less than ideal lumber as best he or she can.
Lumber for constructing buildings and related structures such as exterior decks, porches, garages, and the like must be sufficiently strong to bear considerable weight. Therefore, lumber is too strong for a carpenter or other craftsman to bend into an acceptable configuration by hand. A manual tool to perform such bending is desirable when poor quality lumber is to be incorporated into a structure. The prior art has proposed jacks and similar devices for exerting pushing forces considerably greater than those which can be developed by human strength.
An example is seen in U.S. Pat. No. 5,087,019, issued to Dennis J. Peabody et al. on Feb. 11, 1992. Peabody et al. illustrates a spreader which can expand to exert a pushing force, but in which the device is arranged and acts linearly. That is, the point of anchorage is located colinearly with the axis of the device. This requires that the object receiving the pushing force be moved away from the point of anchorage. In the field of carpentry, it is frequently the case that a board being nailed into the structure being built is not suitably located for a linearly spreader to be effective. In contrast to linear spreaders, the present invention has an automatic clamp which grips a board as it expands to exert force on the board receiving force. The clamp is able to grasp a board not colinearly located with respect to the direction of expansion.
U.S. Pat. No. 5,501,754, issued to Hiroaki Hiraguri on Mar. 26, 1996, shows a device for lifting floor panels. The device of Hiraguri is essentially a linear spreader having structure for engaging floor panels. The engaging structure is located at the point receiving the pushing force. By contrast, the present invention incorporates a clamp which can grasp a supporting object located out of line with the direction of expansion.
U.S. Pat. No. 5,875,606, issued to Lars Dean Jensen on Mar. 2, 1999, describes a wall jack which expands between two opposing wall surfaces when a central screw member is turned. This device lacks a clamp found in the present invention, and cannot grasp one structural member from two sides, as can the device of the present invention.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.